text: /*
  Bullet Continuous Collision Detection and Physics Library
  Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
  
  This software is provided 'as-is', without any express or implied warranty.
  In no event will the authors be held liable for any damages arising from the use of this software.
  Permission is granted to anyone to use this software for any purpose, 
  including commercial applications, and to alter it and redistribute it freely, 
  subject to the following restrictions:
  
  1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
  */
  
  
  #include "btPersistentManifold.h"
  #include "LinearMath/btTransform.h"
  
  
  btScalar					gContactBreakingThreshold = btScalar(0.02);
  ContactDestroyedCallback	gContactDestroyedCallback = 0;
  ContactProcessedCallback	gContactProcessedCallback = 0;
  
  
  
  btPersistentManifold::btPersistentManifold()
  :m_body0(0),
  m_body1(0),
  m_cachedPoints (0),
  m_index1a(0)
  {
  }
  
  
  
  
  #ifdef DEBUG_PERSISTENCY
  #include <stdio.h>
  void	btPersistentManifold::DebugPersistency()
  {
  	int i;
  	printf("DebugPersistency : numPoints %d\n",m_cachedPoints);
  	for (i=0;i<m_cachedPoints;i++)
  	{
  		printf("m_pointCache[%d].m_userPersistentData = %x\n",i,m_pointCache[i].m_userPersistentData);
  	}
  }
  #endif //DEBUG_PERSISTENCY
  
  void btPersistentManifold::clearUserCache(btManifoldPoint& pt)
  {
  
  	void* oldPtr = pt.m_userPersistentData;
  	if (oldPtr)
  	{
  #ifdef DEBUG_PERSISTENCY
  		int i;
  		int occurance = 0;
  		for (i=0;i<m_cachedPoints;i++)
  		{
  			if (m_pointCache[i].m_userPersistentData == oldPtr)
  			{
  				occurance++;
  				if (occurance>1)
  					printf("error in clearUserCache\n");
  			}
  		}
  		btAssert(occurance<=0);
  #endif //DEBUG_PERSISTENCY
  
  		if (pt.m_userPersistentData && gContactDestroyedCallback)
  		{
  			(*gContactDestroyedCallback)(pt.m_userPersistentData);
  			pt.m_userPersistentData = 0;
  		}
  		
  #ifdef DEBUG_PERSISTENCY
  		DebugPersistency();
  #endif
  	}
  
  	
  }
  
  
  int btPersistentManifold::sortCachedPoints(const btManifoldPoint& pt) 
  {
  
  		//calculate 4 possible cases areas, and take biggest area
  		//also need to keep 'deepest'
  		
  		int maxPenetrationIndex = -1;
  #define KEEP_DEEPEST_POINT 1
  #ifdef KEEP_DEEPEST_POINT
  		btScalar maxPenetration = pt.getDistance();
  		for (int i=0;i<4;i++)
  		{
  			if (m_pointCache[i].getDistance() < maxPenetration)
  			{
  				maxPenetrationIndex = i;
  				maxPenetration = m_pointCache[i].getDistance();
  			}
  		}
  #endif //KEEP_DEEPEST_POINT
  		
  		btScalar res0(btScalar(0.)),res1(btScalar(0.)),res2(btScalar(0.)),res3(btScalar(0.));
  		if (maxPenetrationIndex != 0)
  		{
  			btVector3 a0 = pt.m_localPointA-m_pointCache[1].m_localPointA;
  			btVector3 b0 = m_pointCache[3].m_localPointA-m_pointCache[2].m_localPointA;
  			btVector3 cross = a0.cross(b0);
  			res0 = cross.length2();
  		}
  		if (maxPenetrationIndex != 1)
  		{
  			btVector3 a1 = pt.m_localPointA-m_pointCache[0].m_localPointA;
  			btVector3 b1 = m_pointCache[3].m_localPointA-m_pointCache[2].m_localPointA;
  			btVector3 cross = a1.cross(b1);
  			res1 = cross.length2();
  		}
  
  		if (maxPenetrationIndex != 2)
  		{
  			btVector3 a2 = pt.m_localPointA-m_pointCache[0].m_localPointA;
  			btVector3 b2 = m_pointCache[3].m_localPointA-m_pointCache[1].m_localPointA;
  			btVector3 cross = a2.cross(b2);
  			res2 = cross.length2();
  		}
  
  		if (maxPenetrationIndex != 3)
  		{
  			btVector3 a3 = pt.m_localPointA-m_pointCache[0].m_localPointA;
  			btVector3 b3 = m_pointCache[2].m_localPointA-m_pointCache[1].m_localPointA;
  			btVector3 cross = a3.cross(b3);
  			res3 = cross.length2();
  		}
  
  		btVector4 maxvec(res0,res1,res2,res3);
  		int biggestarea = maxvec.closestAxis4();
  		return biggestarea;
  }
  
  
  int btPersistentManifold::getCacheEntry(const btManifoldPoint& newPoint) const
  {
  	btScalar shortestDist =  getContactBreakingThreshold() * getContactBreakingThreshold();
  	int size = getNumContacts();
  	int nearestPoint = -1;
  	for( int i = 0; i < size; i++ )
  	{
  		const btManifoldPoint &mp = m_pointCache[i];
  
  		btVector3 diffA =  mp.m_localPointA- newPoint.m_localPointA;
  		const btScalar distToManiPoint = diffA.dot(diffA);
  		if( distToManiPoint < shortestDist )
  		{
  			shortestDist = distToManiPoint;
  			nearestPoint = i;
  		}
  	}
  	return nearestPoint;
  }
  
  int btPersistentManifold::addManifoldPoint(const btManifoldPoint& newPoint)
  {
  	btAssert(validContactDistance(newPoint));
  
  	int insertIndex = getNumContacts();
  	if (insertIndex == MANIFOLD_CACHE_SIZE)
  	{
  #if MANIFOLD_CACHE_SIZE >= 4
  		//sort cache so best points come first, based on area
  		insertIndex = sortCachedPoints(newPoint);
  #else
  		insertIndex = 0;
  #endif
  		clearUserCache(m_pointCache[insertIndex]);
  		
  	} else
  	{
  		m_cachedPoints++;
  
  		
  	}
  	if (insertIndex<0)
  		insertIndex=0;
  
  	btAssert(m_pointCache[insertIndex].m_userPersistentData==0);
  	m_pointCache[insertIndex] = newPoint;
  	return insertIndex;
  }
  
  btScalar	btPersistentManifold::getContactBreakingThreshold() const
  {
  	return m_contactBreakingThreshold;
  }
  
  
  
  void btPersistentManifold::refreshContactPoints(const btTransform& trA,const btTransform& trB)
  {
  	int i;
  #ifdef DEBUG_PERSISTENCY
  	printf("refreshContactPoints posA = (%f,%f,%f) posB = (%f,%f,%f)\n",
  		trA.getOrigin().getX(),
  		trA.getOrigin().getY(),
  		trA.getOrigin().getZ(),
  		trB.getOrigin().getX(),
  		trB.getOrigin().getY(),
  		trB.getOrigin().getZ());
  #endif //DEBUG_PERSISTENCY
  	/// first refresh worldspace positions and distance
  	for (i=getNumContacts()-1;i>=0;i--)
  	{
  		btManifoldPoint &manifoldPoint = m_pointCache[i];
  		manifoldPoint.m_positionWorldOnA = trA( manifoldPoint.m_localPointA );
  		manifoldPoint.m_positionWorldOnB = trB( manifoldPoint.m_localPointB );
  		manifoldPoint.m_distance1 = (manifoldPoint.m_positionWorldOnA -  manifoldPoint.m_positionWorldOnB).dot(manifoldPoint.m_normalWorldOnB);
  		manifoldPoint.m_lifeTime++;
  	}
  
  	/// then 
  	btScalar distance2d;
  	btVector3 projectedDifference,projectedPoint;
  	for (i=getNumContacts()-1;i>=0;i--)
  	{
  		
  		btManifoldPoint &manifoldPoint = m_pointCache[i];
  		//contact becomes invalid when signed distance exceeds margin (projected on contactnormal direction)
  		if (!validContactDistance(manifoldPoint))
  		{
  			removeContactPoint(i);
  		} else
  		{
  			//contact also becomes invalid when relative movement orthogonal to normal exceeds margin
  			projectedPoint = manifoldPoint.m_positionWorldOnA - manifoldPoint.m_normalWorldOnB * manifoldPoint.m_distance1;
  			projectedDifference = manifoldPoint.m_positionWorldOnB - projectedPoint;
  			distance2d = projectedDifference.dot(projectedDifference);
  			if (distance2d  > getContactBreakingThreshold()*getContactBreakingThreshold() )
  			{
  				removeContactPoint(i);
  			} else
  			{
  				//contact point processed callback
  				if (gContactProcessedCallback)
  					(*gContactProcessedCallback)(manifoldPoint,m_body0,m_body1);
  			}
  		}
  	}
  #ifdef DEBUG_PERSISTENCY
  	DebugPersistency();
  #endif //
  }
  
  
  
  
  
  